The house on Kaukama Road still stands, but the garage connected to it, is a different story.
"The whole garage was destroyed, so it was a quickly-developing fire," said Honolulu Fire Captain Terry Seelig.
Firefighters say a man was working in the garage when flames ignited.
Investigators are looking into what may have sparked the blaze but say it may be automotive in nature.
"A motorcycle may have been in the garage at the time but we're not sure to the sequence of events as to what happened," said Seelig.
The Waianae man in his forties suffered burns on his leg and forearm said emergency officials. He was taken to a local hospital in serious condition.
Neighbors witnessed heavy smoke and flames coming from the garage.
"It was really high, the black smoke, and then the bottom side you could see the flames," said neighbor Tomi Adamio.
Firefighters were able to contain the blaze in ten minutes and stop it from spreading to the adjacent house and neighboring lots.
"The house was radiating heat," said Seelig. "There was little bit of charring on the outside but nothing on the inside."
The house is habitable. Investigators are still trying to determine the exact cause of the fire.